The present invention relates to antimicrobial compositions and methods for use of those compositions in various medical applications. One of the major challenges of modern medical treatment is control of infection and the spread of microbial organisms.
One area where this challenge is constantly presented is in infusion therapy of various types. Infusion therapy is one of the most common health care procedures. Hospitalized, home care, and other patients receive fluids, pharmaceuticals, and blood products via a vascular access device inserted into the vascular system. Infusion therapy may be used to treat an infection, provide anesthesia or analgesia, provide nutritional support, treat cancerous growths, maintain blood pressure and heart rhythm, or many other clinically significant uses.
Infusion therapy is facilitated by a vascular access device. The vascular access device may access a patient's peripheral or central vasculature. The vascular access device may be indwelling for short term (days), moderate term (weeks), or long term (months to years). The vascular access device may be used for continuous infusion therapy or for intermittent therapy.
A common vascular access device is a plastic catheter that is inserted into a patient's vein. The catheter length may vary from a few centimeters for peripheral access, to many centimeters for central access and may include devices such as peripherally inserted central catheters (PICC). The catheter may be inserted transcutaneously or may be surgically implanted beneath the patient's skin. The catheter, or any other vascular access device attached thereto, may have a single lumen or multiple lumens for infusion of many fluids simultaneously.
The vascular access device commonly includes a Luer adapter to which other medical devices may be attached. For example, an administration set may be attached to a vascular access device at one end and an intravenous (IV) bag at the other. The administration set is a fluid conduit for the continuous infusion of fluids and pharmaceuticals. Commonly, an IV access device is a vascular access device that may be attached to another vascular access device, closes the vascular access device, and allows for intermittent infusion or injection of fluids and pharmaceuticals. An IV access device may include a housing and a septum for closing the system. The septum may be opened with a blunt cannula or a male Luer of a medical device.
When the septum of a vascular access device fails to operate properly or has inadequate design features, certain complications may occur. Complications associated with infusion therapy may cause significant morbidity and even mortality. One significant complication is catheter related blood stream infection (CRBSI). An estimate of 250,000-400,000 cases of central venous catheter (CVC) associated BSIs occur annually in US hospitals.
A vascular access device may serve as a nidus of infection, resulting in a disseminated BSI (blood stream infection). This may be caused by failure to regularly flush the device, a non-sterile insertion technique, or by pathogens that enter the fluid flow path through either end of the path subsequent to catheter insertion. When a vascular access device is contaminated, pathogens adhere to the vascular access device, colonize, and form a biofilm. The biofilm is resistant to most biocidal agents and provides a replenishing source for pathogens to enter a patient's bloodstream and cause a BSI. Thus, devices with antimicrobial properties are needed.
One approach to preventing biofilm formation and patient infection is to provide an antimicrobial coating on various medical devices and components. Many medical devices are made with either metallic or polymeric materials. These materials usually have a high coefficient of friction. A low molecular weight material or liquid with a low coefficient of friction is usually compounded into the bulk of the materials or coated onto the surface of the substrates to help the functionality of the devices.
Over the last 35 years, it has been common practice to use a thermoplastic polyurethane solution as the carrier for antimicrobial coatings. The solvent is usually tetrahydrofuran (THF), dimethylformamide (DMF), or a blend of both. Because THF can be oxidized very quickly and tends to be very explosive, an expensive explosion-proof coating facility is necessary. These harsh solvents also attack many of the polymeric materials commonly used, including polyurethane, silicone, polyisoprene, butyl rubber polycarbonate, rigid polyurethane, rigid polyvinyl chloride, acrylics, and styrene-butadiene rubber (SBR). Therefore, medical devices made with these materials can become distorted over time and/or form microcracks on their surfaces. Another issue with this type of coating is that it takes almost 24 hours for the solvent to be completely heat evaporated. Accordingly, conventional technology has persistent problems with processing, performance, and cost.
Another limitation to the use of such devices is the general availability of suitable antimicrobial agents for use in controlling microbial growth. One of the most commonly used antimicrobial agents used in medical devices is silver. Silver salts and silver element are well known antimicrobial agents in both the medical surgical industry and general industries. They are usually incorporated into the polymeric bulk material or coated onto the surface of the medical devices by plasma, heat evaporation, electroplating, or by conventional solvent coating technologies. These technologies are tedious, expensive, and not environmentally friendly.
In addition, the performance of silver coated medical devices is mediocre at best. For example, it can take up to eight (8) hours before the silver ion, ionized from the silver salts or silver element, to reach efficacy as an antimicrobial agent. As a result, substantial microbial activity can occur prior to the silver coating even becoming effective. Furthermore, the silver compound or silver element has an unpleasant color, from dark amber to black.
Vascular access devices of this type may require, or benefit from the use of, a lubricant. A lubricant can be applied to the moveable parts of the device in order to facilitate actuation of the septum. However, with conventional lubricants, bacteria and other microorganisms may also reside in the lubricant. Conventional lubricants are not intended to prevent or significantly inhibit microbial growth and propagation. Indeed, conventional lubricants may play a role in the spread of microbial agents.
Accordingly, there is a need in the art for improved methods for providing antimicrobial capability to medical devices of various types, and particularly devices related to infusion therapy. Specifically, there is a need for an effective antimicrobial lubricant that can be used in connection with various types of medical devices. There is a need for a lubricant that aids in preventing microbial propagation and may be useful and effective in killing microbial agents on contact.